1. Field
Some example embodiments of the present disclosure may relate to sensorless control apparatuses of motors configured to estimate the speed and the position of a rotor by detecting currents that are being input to the motor, and/or control methods thereof.
2. Description of Related Art
A motor is an apparatus used in wide range of fields from household appliances, such as washing machines and refrigerators, to various information processing apparatuses. An apparatus for controlling a motor in general is provided with a separate position sensor that is configured to detect the speed and the position of a rotor of the motor. In contrast, a sensorless control method may refer to a method of estimating the speed and the position of a rotor without using a separate position sensor.
As for the sensorless control apparatus as such, a method provided with a current and voltage model of a motor as the basis thereof may be used, and at the model of the motor as such, parameters such as a resistance of the motor and a magnetic flux by a permanent magnet are used. Here, the parameters such as the resistance of the motor and the magnetic flux of the permanent magnet are changed according to the temperature of the motor, and in a case when the changes of the parameters according to the temperature of the motor are not compensated, the error between the actual motor and the model of the motor is increased, and thereby the performance of estimating the speed and the position of the rotor is reduced.
Particularly, in a case of household appliances, such as washing machines, provided with the large change of the load thereof and the larger temperature change of the motor according to the load, the change of the parameters according to the temperature may significantly degrade the sensorless control performance of the motor. In addition, in a severe case, in a state of the motor being out of step, damage of the motor and an inverter by excess current may be caused.
One of the conventional compensation methods of the parameters used is a method of installing an additional temperature sensor at a motor. The method as such is configured in a way that, through the temperature sensor, the temperature of the motor is observed, and then, according to the observed temperature, the parameters are compensated. The method as such is configured to directly measure the temperature of the motor, but on the other hand, by having the additional temperature sensor, the production cost is increased, and the manufacturing process and the overall structure of the control apparatus become more complicated. As for another conventional compensation method of the parameters being used, through the temperature of an inverter module of the motor, the temperature of the motor is estimated, and by using the estimated temperature of the motor, the parameters are compensated. However, since the method as such is configured in a way that the temperature of the motor is estimated through the temperature of the inverter module, the accuracy in estimating the temperature of the motor and the compensating the parameters is low.